U.S. patent number 5,369,253 [Application Number 08/083,331] was granted by the patent office on 1994-11-29 for heating cooker.
This patent grant is currently assigned to Kabushiki Kaisha Toshiba. Invention is credited to Sachiko Endo, Norisuke Fukuda, Kyoko Kuwata, Koji Murakami, Yukinobu Takahashi.
United States Patent |
5,369,253 |
Kuwata , et al. |
November 29, 1994 |
Heating cooker
Abstract
A heating cooker includes a cooking chamber having a heater for
heating food, a gas sensor for detecting the quantity of vapor
evaporating from the food heated in the cooking chamber, a
temperature sensor for detecting a temperature in the cooking
chamber, and a controller for determined the kind of the food
according to the quantity of vapor detected by the gas sensor, and
for controlling the heating temperature and heating time of the
heater according to the kind of food which has been determined.
Inventors: |
Kuwata; Kyoko (Tokyo,
JP), Endo; Sachiko (Tokyo, JP), Murakami;
Koji (Tokyo, JP), Takahashi; Yukinobu (Tokyo,
JP), Fukuda; Norisuke (Tokyo, JP) |
Assignee: |
Kabushiki Kaisha Toshiba
(Kawasaki, JP)
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Family
ID: |
26453142 |
Appl.
No.: |
08/083,331 |
Filed: |
June 29, 1993 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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690846 |
Apr 26, 1991 |
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Foreign Application Priority Data
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Apr 28, 1990 [JP] |
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2-114389 |
Jul 30, 1990 [JP] |
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2-199144 |
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Current U.S.
Class: |
219/707; 219/708;
219/710; 219/704; 99/325; 219/400; 219/712 |
Current CPC
Class: |
F24C
7/087 (20130101) |
Current International
Class: |
F24C
7/08 (20060101); H05B 006/50 () |
Field of
Search: |
;219/707,702,704,708,709,710,712,400,492 ;99/325,330,333,468 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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0024798 |
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Mar 1981 |
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EP |
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0074764 |
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Mar 1983 |
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EP |
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0078607 |
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May 1983 |
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EP |
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0238022 |
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Sep 1987 |
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EP |
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0289000 |
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Nov 1988 |
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EP |
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2509108 |
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Jan 1983 |
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FR |
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1-239322 |
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Sep 1989 |
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JP |
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Primary Examiner: Reynolds; Bruce A.
Assistant Examiner: Hoang; Tu
Attorney, Agent or Firm: Foley & Lardner
Parent Case Text
This application is a continuation of application Ser. No.
07/690,846, filed Apr. 26, 1991, now abandoned.
Claims
What is claimed is:
1. A heating cooker comprising:
(a) a cooking chamber having a heater for heating an object;
(b) a gas sensor located in said cooking chamber for detecting gas
or vapor evaporating from the object being heated in said cooking
chamber, said gas sensor producing an output which is indicative of
a quantity of gas or vapor evaporating from the object being
heated;
(c) a temperature sensor molted proximate to said gas sensor for
detecting a temperature around said gas sensor in said cooking
chamber; and
(d) control means for controlling electric supply to said
heater,
said control means 1) measuring a first output (V0) of said gas
sensor at a start of cooking, 2) measuring a second output (V1) of
said gas sensor after the inside of said cooking chamber attains a
set temperature which is lower than a lowest cooking temperature
specifically associated with the object being heated, 3) adjusting
said electric supply to heat the object at a temperature (t2) for a
set time, 4) thereafter measuring a third output value (V2) of said
gas sensor, 5) determining a kind of the object based on the first
and second outputs (V0 and V1) 6) adjusting said electric supply to
heat the object at a cooking temperature and for a cooking time
which are each calculated based on the first, second, and third
output values (V0, V1, and v2).
2. The heating cooker according to claim 1, wherein the temperature
in said cooking chamber at the start of cooking is a room
temperature.
3. The heating cooker according to claim 1, wherein the temperature
in said cooking chamber at the start of cooking is a temperature
attained after preheating.
4. The heating cooker according to claim 1, wherein the food is one
of a bread and a cake.
5. A heating cooker comprising:
(a) a cooking chamber in which a food is placed for cooking;
(b) a heater provided in said chamber for heating said food;
(c) a gas sensor provided in said chamber for detecting a quantity
of vapor in said chamber during cooking of said food;
(d) a temperature sensor located proximate to said gas sensor and
provided in said chamber for detecting a temperature around said
gas sensor in said chamber; and
(e) control means operatively connected to said temperature sensor,
said gas sensor and said heater, for determining a kind of the food
based on outputs of said gas sensor and said temperature sensor,
and for controlling operation of said heater in accordance with the
kind of the food,
wherein said control means receives a detected temperature in said
chamber at a start of cooking and corrects the quantity of vapor
detected by said gas sensor based on the detected temperature in
said chamber at the start of cooking.
6. The heating cooker according to claim 5, wherein the temperature
in said cooking chamber at the start of cooking is a room
temperature.
7. The heating cooker according to claim 5, wherein the temperature
in said cooking chamber at the start of cooking is a temperature
attained after preheating.
8. The heating cooker according to claim 5, wherein the food is one
of a bread and a cake.
9. The heating cooker according to claim 8, wherein the heating
cooker is an electronic oven.
10. A heating cooker comprising:
(a) a cooking chamber in which a good is placed for cooking;
(b) a heater provided in said chamber for heating said food;
(c) a gas sensor provided in said chamber for detecting a quantity
of vapor occurring in said chamber during cooking of said food;
(d) a temperature sensor provided in said chamber and located
proximate to said gas sensor for detecting a temperature around
said gas sensor in said chamber; and
(e) control means operatively connected to said temperature sensor,
said gas sensor and said heater, for determining a kind of the food
based on outputs of said gas sensor and said temperature sensor and
for controlling operation of said heater in accordance with the
kind of the food,
wherein said control means controls said heater to start cooking
said food, controls said gas sensor to detect the quantity of vapor
at first and second outputs of said gas sensor which are obtained
at said first and second points in time, respectively.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a heating cooker, and particularly
to a technique of automatically baking cakes, etc., with the
heating cooker.
2. Description of the Prior Art
A heating cooker such as an electronic oven generally has a
grilling function and an oven function. The grilling function is
achieved with a flat heater attached to the ceiling of the cooker
to cook fish, meat, etc., with radiant heat, while the oven
function is achieved with a sirocco fan and a sheathed heater
arranged on the back of a heating chamber of the cooker to bake
bread, cakes, etc., with hot air circulated in the cooking
chamber.
To automatically control the grilling and oven functions, a
conventional technique employs a weight sensor. With the weight
sensor, the technique measures a total of the weight of food to be
cooked and the weight of container of the food, calculates a
heating time according to the total weight, and after the elapse of
the heating time, automatically stops heating the food. Another
conventional technique employs a weight sensor to calculate a base
time and a temperature sensor to detect vapor evaporating from
heated food and to calculate an additional heating time, from which
the technique determines a total heating time.
Food, particularly bread or a cake must be baked under careful
control to form air bubble inside it. In automatically baking the
bread or the cake, the above conventional techniques raise the
following problems:
1) If no preheating is done or if the cooking chamber is not
sufficiently cooled, the conventional techniques cannot correctly
calculate a heating time of the bread or the cake. After repetitive
use of the oven, bread or cakes may be overbaked. Under the
increasing need of cooking with no preheating, this problem is
serious.
2) The conventional techniques restrict the weight of a container
of food to be cooked. Cake molds may be made of stainless steel,
heat-resistant glass, aluminum, paper, etc., which have different
weight. The weight sensor of the conventional techniques restricts
the material of the container. If it is unrestricted, the
conventional control techniques may be useless because the weight
sensor measures a total of the weight of a mold and the weight of
food contained in the mold. Namely, the baking of bread or a cake
is greatly influenced by the weight of a mold to be used for baking
the bread or the cake. If the mold is light weight, a baking time
may become shorter to make the bread or the cake half-baked.
3) The weight sensor must be connected with a top plate of the
cooker. This arrangement limits the size of the top plate so that a
space in the cooking chamber may not effectively be used. Compared
with a usual square top plate, the top plate of the above
techniques must have limited size and shape which may reduce the
quantity of food to be cooked on the top plate. It is possible to
employ a special top plate, but it may increase the number of
accessories and the cost and deteriorate handling convenience of
the cooker.
4) The control means employed by the above techniques includes only
the weight sensor. This limits a base time for each menu. This
means that a menu which is selected with one selection key of the
cooker does not have flexibility in cooking times. For example,
there are various kinds of cakes such as sponge cakes, pound cakes,
madeleines, and roll cakes. The automatic control of the
conventional techniques, however, cannot deal with a variety of
these cakes because they involve different heating times.
Thus, the conventional automatic cooking techniques for the heating
cooker, such as the electronic oven employing the weight sensor,
have the problems of setting an improper heating time for
repetitive use, limiting the size of the top plate of the cooker to
spoil effective use of space in the cooking chamber, being
influenced by the weight of a container for the food to be cooked,
and limiting the flexibility of cooking time for each menu.
SUMMARY OF THE INVENTION
To solve the above problems, an object of the invention is to
provide a heating cooker which can deal with various menus using a
single automatic cooking key and can achieve stabilized cooking
even when no preheating is used (insert 2) repetitive heating is
utilized.
Another object of the invention is to provide a heating cooker
which can 1) cook a variety of menus such as for different baking
cakes using one automatic cooking key, 2) accurately identify the
kind of a cake to be baked, and 3) properly bake the cake.
Still another object of the invention is to provide an electronic
oven which detects the concentration of a gas or vapor evaporating
from heated food such as a cake, as well as a change in the
concentration of the gas to determine the kind of cake, and
according to the determined kind, controls a heater to
automatically bake the cake.
In order to accomplish the above objects, a heating cooker
according to a first aspect of the invention includes a gas sensor
for detecting vapor evaporating from food heated in a cooking
chamber of the cooker, and a temperature sensor for detecting a
temperature in the cooking chamber. Based on the outputs of these
sensors, a heater is controlled to maintain a set temperature in
the cooking chamber. The quantity of vapor evaporating from the
food detected by the gas sensor determines the kind of food to be
cooked, and the food is automatically cooked according to the
determined kind.
The surface area of the food to be cooked greatly influences the
quantity of vapor evaporating from the food as well as the heating
time of the food. For example, to make a roll cake, dough is poured
large and thick onto a top plate of the cooker, is baked, and then
rolled into a roll. On the other hand, to make a sponge cake or a
pound cake, dough is poured thick into a mold and baked. A thin
cake such as the roll cake having a large surface area must be
baked in a short time at a high temperature, while a thick cake
such as the pound cake having a small surface area must be baked in
a longer time longer at a low temperature.
The first aspect of the invention satisfies these requirements. The
heating cooker according to the first aspect of the invention
detects the surface area of food to be cooked from the quantity of
vapor evaporating from the food, and determines the heating
conditions of the food according to the detected surface area.
The first aspect of the invention controls the heated of the cooker
to maintain a set temperature in the cooking chamber, detects the
quantity of vapor evaporating from food to be cooked, determines
the kind of the food according to the vapor quantity, and
calculates additional heating time and temperature according to the
determined kind of the food, thereby automatically cooking the
food. This aspect of the invention precisely controls with a
control key to properly cook food.
The cooker of this aspect of the invention involves weight sensor,
and therefore, improves the degree of freedom of designing and
increase a cooking space in the cooker.
A heating cooker according to a second aspect of the invention
comprises a gas sensor for detecting vapor evaporating from food
heated in a cooking chamber of the cooker, and a temperature sensor
for detecting a temperature around the gas sensor. These sensors
detect a temperature in the cooking chamber at the start of a time
necessary for attaining a predetermined temperature, and the
quantity of vapor evaporating from the food to be cooked. The
quantity of vapor is corrected according to the temperature in the
cooking chamber at the start of cooking and the time necessary for
attaining the predetermined temperature. Based on the corrected
vapor quantity, an additional heating time is calculated to
automatically cook the food.
The second aspect of the invention corrects the vapor quantity
detected by the gas sensor according to the temperature around the
gas sensor at the start of cooking, thereby properly cooking the
food even under repetitive heating or even if the inside of the
cooking chamber is not sufficiently cooled. In this way, the second
aspect of the invention can better control cooking depending on
food to be cooked.
A temperature at which the gas sensor detects the quantity of vapor
is preferable to be a lowest cooking temperature. Once this lowest
cooking temperature is attained, a heating time and a heating
temperature that follow will be determined to cook food properly
and efficiently.
A heating cooker according to a third aspect of the invention
comprises a cooking chamber for cooking food with heat generated by
a heater, a gas sensor for detecting a gas or vapor evaporating
from the food heated in the cooking chamber, a temperature sensor
for detecting a temperature in the cooking chamber, a controller
for controlling the heater, and a judging unit for determining the
kind of the food according to outputs of the gas sensor and thereby
determining a cooking temperature and a cooking time, the
controller measures an output V1 of the gas sensor after the
cooking chamber attains a set temperature which is lower than a
lowest cooking temperature determined by the kind of the food. The
controller then heats the food for a set time at a temperature t2,
calculates a difference (V1-V2) between the output value V1 and
another output V2 of the gas sensor detected thereafter, finds the
volume of the food from the values V1 and (V1-V2) to judge the kind
of the food, determines a cooking temperature and a cooking time
according to the judged kind, and heats the food at the determined
temperature for the determined time.
As explained before, the quantity of vapor evaporating from food to
be cooked is greatly influenced by the surface area of the food.
Also, a heating time of the food is influenced by the surface area
and volume of the food.
A large surface area is equivalent to a large evaporating area to
which easily produces vapor. If a cake to be baked with the cooker
has a large surface area, it produces a large quantity of vapor
initially. If the volume of a cake is large, it continuously
produces vapor until it is baked to some extent. The larger the
volume of a cake, the larger a change occurring in the quantity of
vapor evaporating from the cake.
A roll cake and a sponge cake are made from substantially the same
ratio of ingredients of egg flour, sugar, and butter which are
mixed together but baked in different shapes. Namely, to make the
roll cake, the materials are poured thin onto a top plate of the
cooker, baked, and rolled into a roll. On the other hand, to make
the sponge cake, the materials are poured thick into a baking mold
and baked.
The roll cake has a large surface area and is thin so that it has a
large evaporating area to easily produce vapor. The roll cake,
therefore, produces a large quantity of vapor at first and is baked
in a short time, so that the quantity of vapor from the roll cake
may decrease quickly after a certain time and arrive at a constant
value. This means that the quantity of vapor from the roll cake
changes in a very short arrive at. This sort of cake having a large
surface area and being thin, must be baked at a high temperature
time.
On the other hand, the sponge cake has a small surface area and is
thick so that it takes a relatively long time to bake, and the
quantity of vapor evaporating from the sponge cake changes more
smoothly. Accordingly, it produces a small quantity of vapor at
first. After that, the quantity of vapor changes widely. This sort
of cake having a small surface area and being thick must be baked
in a long period of time.
Compared with the sponge and roll cakes, a pound cake uses more
butter and is made from a different ratio of ingredients. This
difference in the ingredients, however, can be substantially
ignored when measuring the quantity vapor. Namely, baking
conditions of the pound cake are largely influenced by its shape
and size.
In view of these points, the third aspect of the invention detects
the surface area of food to be cooked with the cooker according to
the quantity of vapor evaporating from the food at a predetermined
temperature, detects the volume of the food according to a change
in the quantity of vapor, and precisely determines heating
conditions of the food according to the obtained data..
Since the third aspect of the invention detects the quantity of
vapor at different occasions, it can correctly judge the kind of a
cake to be baked even if the quantity of vapor fluctuates; and can
bake the cake depending on the shape and size of a mold of the
cake.
These and other objects, features and advantages of the invention
will be more apparent from the following detailed description of
preferred embodiments in conjunction with the accompanying
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIGS. 1 and 2 are schematic views showing an electronic oven
according to a first embodiment of the invention;
FIG. 3 is a view showing a rate of change of outputs of a gas
sensor of the oven in baking sponge cakes with different initial
temperatures in a cooking chamber of the oven;
FIG. 4 is a view showing a rate of change of outputs of the gas
sensor in baking cakes with no preheating;
FIG. 5 is a view showing a rate of change of outputs of the gas
sensor and an additional heating time after the cooking chamber has
attained 160.degree. C. in baking various cakes;
FIG. 6 is a view showing a relationship between a total heating
time T and a rate of change of outputs of the gas sensor;
FIG. 7 is a flowchart showing an operation of the first
embodiment;
FIGS. 8 and 9 are views showing an electronic oven according to a
second embodiment of the invention;
FIG. 10 is a view showing a relationship between an optimum heating
temperature and an optimum cooking time for various cakes such as
roll cakes and sponge cakes baked with the oven;
FIG. 11 is a view showing a rate of change of outputs of a gas
sensor of the oven with respect to the surface area of each cake to
be baked, for a range extending from the start of heating to a
point where a cooking chamber of the oven attains a predetermined
temperature in baking cakes such as sponge cakes with the oven;
FIG. 12 is a view showing a rate of change of outputs of the gas
sensor and an additional heating time after the cooking chamber has
attained 160.degree. C. in baking various cakes;
FIG. 13 is a view showing a relationship between a rate of change
of outputs of the gas sensor and a total heating time in baking
various cakes;
FIG. 14 is a flowchart showing an operation of the second
embodiment;
FIG. 15 is a view showing two heating sequences to be selected in
the flowchart of FIG. 14;
FIGS. 16 and 17 are views showing changes in resistance of the gas
sensor in the two heating sequences of FIG. 15, respectively;
FIGS. 18a and 18b are views showing an electronic oven according to
a third embodiment of the invention;
FIGS. 19 to 20 are graphs explaining the principle of the third
embodiment;
FIG. 25 is a flowchart showing an operation of baking a cake with
the oven of the third embodiment; and
FIGS. 26a to 26c are views explaining control processes of FIG.
25.
DETAILED DESCRIPTION OF THE EMBODIMENTS
FIGS. 1 and 2 are views showing a heating cooker, i.e., an
electronic oven according to the first embodiment of the invention,
in which FIG. 2 is a perspective view. The electronic oven (heating
cooker) includes a cabinet 1 and a vertically opening door 2 fitted
to the cabinet 1. The cabinet 1 defines a cooking chamber 12 which
includes a heater 7 fitted to the ceiling of the chamber. A control
panel 3 is arranged on the use of side of the door 2. Auto-keys 4
are arranged on the operation panel 3. A user may select and
automatically cook a required menu through the auto-keys 4.
An automatic cooking instruction entered through the auto-keys 4 is
decoded by a controller 5. A driver 6 supplies electricity to the
heater 7. An exhaust duct 8 is disposed inside the cabinet 1. In
the exhaust duct 8, there are arranged a gas sensor 9 for detecting
vapor evaporating from food 13 which is heated in the cooking
chamber 12, and a temperature sensor 10 for detecting a temperature
around the gas sensor 9. A detecting circuit 11 detects a
temperature in the cooking chamber 12 at the start of cooking, a
time necessary for attaining a predetermined temperature, and the
quantity of vapor evaporating from the food 13 when the
predetermined temperature is attained. The controller 5 corrects
the quantity of vapor detected when the predetermined temperature
is attained according to the temperature in the cooking chamber 12
detected at the start of cooking, and calculates an additional
heating time according to the corrected value.
Based on the information detected through the temperature sensor
10, the controller 5 keeps the temperature inside the cooking
chamber 12 constant, and automatically terminates the heating of
the food 13 after the additional heating time.
FIG. 3 shows a rate of change of outputs of the gas sensor 9 in
baking sponge cakes with different initial temperatures in the
cooking chamber 12. In the figure, an abscissa represents a heating
time, and an ordinate indicates the rate of change of outputs of
the gas sensor 9. This rate is based on outputs of the gas sensor 9
measured when the temperature in the cooking chamber 12 reaches
160.degree. C. As shown in FIG. 3, when an initial temperature in
the cooking chamber 12 is high, the rate of change of the outputs
of the gas sensor 9 is large. It is understood from this that the
gas sensor 9 is temperature dependent.
FIG. 4 shows a rate of change of outputs of the gas sensor 9 with
respect to different initial temperatures, in which a temperature
of about 30.degree. C. around the gas sensor 9 with no preheating
is set as 100.
FIG. 5 shows a rate of change of outputs of the gas sensor 9 and an
additional heating time after the cooking chamber 12 attains
160.degree. C. in baking various cakes such as pound cakes, sponge
cakes, madeleines, and roll cakes.
FIG. 6 is based on FIG. 5 and shows a relationship between a total
heating time T and the rate of change of outputs of the gas sensor
9 in baking the various cakes such as the pound cakes, sponge
cakes, madeleines, and roll cakes.
Baking a sponge cake with use of the electronic oven (heating
cooker) of the first embodiment will be explained with reference to
a flowchart of FIG. 7.
Materials of the sponge cake are kneaded and poured into a baking
mold. The mold is placed in the oven. A user pushes one of the
auto-keys 4 on the control panel 3 in front of the cabinet 1, and
pushes a start button to energize the heater 7. Before the
energization of the heater 7, the temperature sensor 10 measures a
temperature T0. (Measuring step 101)
Heating starts. (Heating step 102)
When the temperature sensor 10 measures 160.degree. C. the gas
sensor 9 provides an output Rs. (Measuring step 103)
The output Rs is corrected with the heating start temperature T0 to
calculate a corrected value of .gamma.=Rs.alpha.TO where .alpha. is
a constant. (Correcting step 104)
Based on the corrected value .gamma., the kind of the cake is
identified. (Identifying step 105)
An additional heating time T2=.beta..gamma.(.beta. being a
constant) is determined according to the corrected value .gamma..
(Additional heating time determining step 106)
The additional heating time T2 is informed to the driver 6 to
additionally energize the heater 7, thereby completing the baking
of the cake. (Additional heating step 107)
In this way, the cake is automatically baked under good
controllability. Even if an initial condition in the cooking
chamber 12 differs or the chamber is repeatedly heated, a heating
time is automatically corrected to cook food optimally. The cooker
of the first embodiment can automatically cook food irrespective of
the kind of a container and the materials of the food, and
optimally correct a heating time for different menus to cook
various menus.
The second embodiment of the invention will be explained.
FIGS. 8 and 9 show an electronic oven (heating cooker) according to
the second embodiment of the invention, in which FIG. 9 is a
perspective view. This electronic oven is basically the same as
that of the first embodiment. A temperature sensor 10 for detecting
a temperature in a cooking chamber 12 is disposed, however, in the
vicinity of food 13 instead of in the vicinity of a gas sensor 9.
An output of a heater 7 is controlled according to a value detected
by the temperature sensor 10 to keep a temperature in the cooking
chamber 12 at a set temperature. The gas sensor 9 detects vapor
evaporating from the food 13 heated in the cooking chamber 12 to
measure the quantity of the vapor from the food 13. According to
the quantity of the vapor, the kind of the food 13 is determined,
and according to the determined kind, an additional heating time
and a heating temperature are determined to automatically cook the
food 13.
Similar to the first embodiment, the electronic oven (heating
cooker) comprises a cabinet 1 and a vertically opening door 2
fitted to the cabinet 1. The cabinet 1 defines the cooking chamber
12 having the heater 7 attached to the ceiling. A control panel 3
is arranged on the side of the door 2, and auto-keys 4 on the
control panel 3. A user can select and automatically cook a
required menu through the auto-keys 4.
An automatic cooking instruction entered through the auto-keys 4 is
decoded by a controller 5. A driver 6 supplies electricity to the
heater 7. An exhaust duct is disposed in the cabinet 1. Inside the
exhaust duct 8, there is arranged the gas sensor 9 for detecting
vapor evaporating from the food 13 being heated in the cooking
chamber 12. The temperature sensor 10 detects a temperature around
the food 13 in the cooking chamber 12. A detecting circuit 11
detects a temperature in the cooking chamber 12 at the start of
cooking, a first quantity of vapor evaporating from the food 13 at
the start of cooking, a time necessary for attaining a
predetermined temperature, and a second quantity of vapor
evaporating from the food 13 when the predetermined temperature is
attained. Based on the first and second vapor quantities, the
controller 5 finds a rate of change of the vapor quantities,
identifies the kind of the food according to the rate of change,
and determines an additional heating time and a heating temperature
for the heater 7 accordingly.
According to the information detected by the temperature sensor 10,
the controller 5 keeps a temperature in the cooking chamber 12
constant, and after the additional heating time, automatically
terminates the cooking of the food 13.
FIG. 10 shows a relationship between an optimum heating temperature
and an optimum cooking time of various cakes such as roll cakes and
sponge cakes. The sponge cake is made by pouring dough in a mold
and by baking it. The dough in the mold has a small surface area
and is thick. On the other hand, the roll cake is baked thin with a
large surface area. Although the sponge cake and roll cake have
substantially the same ingredients, the sponge cake must be baked
at a lower temperature for a longer time compared with the roll
cake. Repetitive tests made on madeleines and pound cakes tell that
the baking conditions of the cakes depend on the surface areas of
the cakes, irrespective of their ingredients which may differ from
one to another.
FIG. 11 shows a rate of change of outputs of the gas sensor 9
between the start of heating and an instance when a predetermined
temperature is attained in baking various cakes. In the figure, an
abscissa represents the surface area of a cake, and an ordinate
indicates the rate of change of outputs of the gas sensor 9. This
rate is based on outputs of the gas sensor 9 measured when a
temperature in the cooking chamber 12 reaches 160.degree. C. It is
understood from the figure that the rate of change of the outputs
the gas sensor 9 becomes smaller as the surface area of the cake
becomes larger. This means that the gas sensor 9 is temperature
dependent.
FIG. 12 shows a rate of change of outputs of the gas sensor 9 and
an additional heating time after a temperature in the cooking
chamber 12 reaches 160.degree. C. in baking various cakes such as
pound cakes, sponge cakes, madeleines, and roll cakes.
FIG. 13 is based on FIG. 12 and shows a relationship between a
total heating time T and the rate of change of outputs of the gas
sensor 9 in baking the various cakes such as the pound cakes,
sponge cakes, madeleines, and cakes.
The cakes such as the pound cakes and sponge cakes having a small
surface area must be baked at a low temperature (160.degree. C.) in
a long time, while the cakes such as madeleines and roll cakes
having a large surface area mull be baked at a high temperature
(180.degree. C.) in a short time.
To achieve this, the second embodiment judges, according to the
rate of change of outputs of the gas sensor 9, whether or not food
in the cooking chamber 12 is the pound cake or sponge cake having a
small surface area or the madeleine or roll cake having a large
surface area. If the food is judged to be the madeleine or roll
cake having a large surface area, the temperature is further
increased as shown in FIG. 15 to bake the food for a predetermined
time.
Baking a cake with use of the electronic oven (heating cooker) of
the second embodiment will be explained with reference to a
flowchart of FIG. 14. FIG. 15 shows two heating sequences to be
selected in the flowchart of FIG. 14.
Materials of the cake are kneaded and poured into a baking mold.
The mold is placed in the oven. A user pushes one of the auto-keys
4 on the control panel 3 in front of the cabinet 1, and pushes a
start button.
(Cooking start step 201)
As soon as the start button is pushed, the heater 7 is energized.
(Energizing step 202).
The temperature sensor 10 measures a temperature TO at the
energization, and the gas sensor 9 provides an output R0 (a first
quantity of vapor). (Measuring steps 203 and 204)
Outputs of the temperature and gas sensors are transferred to the
controller 5 through the detecting circuit 11, and stored therein
as initial values.
When the temperature sensor 10 detects 160.degree. C. after the
start of heating, the gas sensor 9 provides an output Rs second
quantity of vapor). (Measuring step 205)
A rate "Rs/R0" of change of outputs of the gas sensor 9 is
calculated according to the value obtained when the temperature
sensor 10 detected 160.degree. C. and the value detected at the
start of heating.
It is checked to see whether or not the rate Rs/R0 is greater than
a predetermined value Ra. (Comparison step 206)
If it is greater than Ra, it is judged that the food is a cake
having a small surface area, for example, a sponge cake or a pound
cake. (Judging step 207)
Thereafter, an instruction of continuously heating the food at a
heating temperature Ta is sent to the driver 6.
(Instruction step 208)
At the same time, an additional heating time T2 is determined
according to the rate Rs/R0. (Additional heating time determining
step 209)
The additional heating time T2 is sent to the driver 6, thereby
completing the cooking. (Additional heating step 210)
FIG. 16 shows a rate of change of resistance of the gas sensor 9
for the above example.
If the rate Rs/R0 is smaller than the predetermined value Ra in the
comparison step 206, it is determined that the food is a cake
having a large surface area, for example, a roll cake or a
madeleine. (Judging step 307.)
An instruction of continuously heating the food at a heating
temperature Tb is sent to the driver 6.
(Instruction step 308)
At the same time, an additional heating time T2 is determined
according to the rate Rs/R0. (Additional heating time determining
step 309)
The additional heating time T2 is sent to the driver 6 to
continuously heat the food until it is completely cooked.
(Additional heating step 310)
FIG. 17 shows a rate of change of resistance of the gas sensor 9
for the above example.
In this way, the cake can automatically and easily be baked under
good controllability irrespective of the kind and material of a
container of the cake. The cooker (electronic oven) of the second
embodiment can optimally correct a heating time for different menus
in cooking various menus.
The second embodiment explained above involves two kinds of cooking
conditions. This invention can handle more than three kinds of
cooking conditions in automatically cooking food. In this case, the
temperature at which the quantity of vapor is detected may be set
lower than a lowest cooking temperature.
The first and second embodiments of the invention control a cooking
temperature and a cooking time of food according to an output of
the gas sensor 9 provided when the predetermined temperature is
attained, so that the food may precisely be controlled and cooked
with one control key. Since the embodiments require no weight
sensor, they improve the degree of freedom of designing and expands
a space to be used for cooking in the cooker.
The third embodiment of the invention will be explained with
reference to FIGS. 18 through 26.
FIGS. 18a and 18b show an electronic oven (heating cooker)
according to the third embodiment of the invention, in which FIG.
18a is a vertical section, and FIG. 18b is a side section. The
electronic oven comprises a cooking chamber 20 for heating food 21
with a heater 18, and a vertically opening door 24. A control panel
22 is arranged on the side of the door 24. Selection keys 23 are
arranged on the panel 22. A user can select and automatically cook
a required menu through the keys 23.
A gas in the cooking chamber 20 is partly exhausted to an exhaust
duct 33 through an exhaust port 32 and to the outside. In the
exhaust duct 33, a gas sensor 35 is arranged to detect vapor or a
gas. A temperature sensor 25 is arranged at an upper part of the
cooking chamber 20. The exhaust duct 33 is arranged above a heating
table 43 on which the food 21 is placed, so that a gas such as
vapor which is lighter than air may stay at an upper part of the
cooking chamber 20. This arrangement increases a concentration of
the gas around the exhaust duct 33.
According to the information detected by the temperature sensor 25
and gas sensor 35, a controller (not shown) keeps a temperature
inside the cooking chamber 20 constant, and automatically
terminates the heating of the food 21 after the elapse of an
additional heating time.
An operation of baking a cake with use of the electronic oven
(heating cooker) of the third embodiment will be explained.
FIG. 19 shows outputs of the gas sensor 35, i.e., gas concentration
rates V1/V0 (V0 being a reference value) measured at a set
temperature ta.degree. C. for pound cakes, sponge cakes,
madeleines, and roll cakes. To make a roll cake, dough is poured
thin onto a top plate, baked, and rolled into a roll. To make a
madeleine, a sponge cake, or a pound cake, dough is poured thick
into a baking mold and baked. The madeleine, sponge cake, and pound
cake become thinner in this order, and their surface areas decrease
in the order of roll cake, madeleine, sponge cake, and pound cake.
Due to the differences in the surface areas, the cakes produce
vapor of different concentrations. This is the reason why the kinds
of the cakes can be determined with use of the gas sensor 35.
As shown in FIG. 20, a difference, i.e., the width of change of gas
concentration after time Tc becomes larger as the volume of the
cake increases.
As shown in FIGS. 21 and 23, the values V1/V0 tell, to some extent,
the kinds of the cakes, for example, the roll cake (course B), and
the pound cake or the sponge cake (course A).
The cake such as the roll cake and madeleine having a large surface
area and being thin must be baked at a high temperature in a short
time. The cake such as the pound cake and sponge cake having a
small surface area and being thick must be baked at a low
temperature for a long time. Namely, an additional heating time T2
is determined depending on the courses A and B.
Due to a slight difference in the shapes of molds of the cakes or
due to intrinsic differences of the sensor and ovens, output values
of the gas sensor 35 may sometimes come on a boundary ranging from
X1 to X2 between the courses A and B. In this case, it is difficult
to judge whether the cake belongs to the course A or B.
For a course C, a cake is baked at a set temperature tc for a set
time Tc as shown in FIGS. 22 and 24. After the time Tc, the gas
sensor 35 provides an output V2, and (V1-V2)/V0 is calculated.
According to T2=.gamma.(V1-V2)/V0+.gamma.' or
T2=.delta.(V1-V2)/V0+.delta.', an additional heating time is
determined, and the heating temperature is changed to Ta or Tb.
Here .gamma., .gamma.', .delta., and .delta.' are constants.
For example, a cake such as the pound cake and sponge cake having a
small surface area must be baked at a low temperature (160.degree.
C.) for a long time, while a cake such as the madeleine and roll
cake having a large surface area must be baked at a high
temperature (180.degree. C.) in a short time.
Based on a rate of change of outputs of the gas sensor 35, it is
judged whether a cake in the cooking chamber 20 is the pound cake
or sponge cake having a small surface area, or the madeleine or
roll cake having a large surface area. If the cake is the madeleine
or roll cake having a large surface area, the temperature is
further increased and the cake is continuously baked for a
predetermined time.
An object of the automatic control of the third embodiment is to
correctly determine the additional heating time.
An operation of baking a sponge cake with use of the electronic
oven (heating cooker) of the third embodiment will be explained
with reference to a flowchart of FIG. 25 and diagrams of FIGS. 26a
and 26b showing a relationship between temperature, outputs of the
gas sensor 35, and time.
When one of the selection keys 23 for automatic cooking is
operated, the heater 18 starts to operate to heat the cooking
chamber 20 to a preheating temperature t0.degree. C. (Preheating
starting step 401)
Meanwhile, materials of, for example, a sponge cake to be baked are
prepared and poured into a baking mold.
When a temperature detected by the temperature sensor reaches t0,
the gas sensor 35 provides an output V0.
(Step 402)
The preheating process then ends. (Step 403)
The door of the oven is opened, and the sponge cake dough 21 with
the baking mold is placed on a heating table (top plate) 43, and
set in the cooking chamber 20. Thereafter, the start key is
operated to restart the heater 18. (Step 404)
When a temperature detected by the temperature sensor indicates a
value ta, the gas sensor 35 provides an output V1. (Step 405)
A value of V1/V0 is compared with reference values x1 and x2 to
determine a course. (Judging step 406)
If V1/V0.gtoreq.X1, it is judged that the course is A for a sponge
cake to start the heater 18 at a cooking temperature ta for a
cooking time T2=.alpha.(V1-V2)/V0+.alpha.'. (Step 407)
The cooking then ends. (End step 408)
If X2.gtoreq.V1/V0<X1 in the judging step 406, it is judged that
the course is C, and the cake is heated at a set temperature to for
a set time Tc. (Step 409)
After the elapse of the time Tc, the gas sensor 35 provides an
output V2. (Step 410)
Based on V2, (V1-V2)/V0 is calculated and judged whether or not it
is larger than a value y. (Judging step 411)
If it is judged that (V1-V2)/V0.gtoreq.y, the cake is additionally
heated at a cooking temperature ta for a time
T2=.gamma.(V1-V2)/V0+.delta.'. (Step 412)
The cooking then ends. (End step 408)
If it is judged that (V1-V2)/V0<y in the judging step 411, the
cake is additionally heated at a cooking temperature tb for a time
T2=.delta.(V1-V2)/V0+.delta.'. (Step 413)
The cooking then ends. (End step 408)
If it is V1/V0<X2 in the judging step 406, it is judged that the
course is B for a roll cake, and the heater 18 is operated at a
cooking temperature tb for a cooking time
T2=.beta.(V1-V2)/V0+.beta.'. (Step 414)
The cooking then ends. (End step 408)
In this way, heating conditions are determined more precisely
according to both the gas concentration and its rate of change so
that the cake may easily automatically be baked under good
controllability irrespective of the kind and material of a
controllability irrespective of the kind and material of a
container of the cake. The cooker (electronic oven) of the third
embodiment can optimally correct a heating time for different menus
to cook various menus.
The above embodiment relates to the grilling function of the cooker
(electronic oven). This invention is applicable also for an oven
function for circulating hot air with a fan. In this case, before
measuring the quantity of vapor, the fan is stopped to keep the
vapor around the gas sensor. Thereafter, the quantity of vapor is
measured. This realizes precise measurement of the quantity of
vapor.
As explained above, the third embodiment involves two kinds of
conditions to be set. This invention can handle more than three
kinds of conditions for automatically cooking food.
The third embodiment has been explained with reference to the
automatic cooking of cakes. The present invention is not limited to
the cakes but applicable for baking various kinds of bread having
different surface areas and sizes, as well as other dishes.
The gas sensor of the electronic oven (heating cooker) may commonly
be used for achieving the oven function.
As explained above, the heating cooker according to the third
embodiment of the invention comprises the gas sensor for detecting
a gas produced from a cake. According to the detected quantity of
the gas, the kind of the cake is determined to automatically set a
heating temperature and a heating time, based on which the cake is
baked. The concentration of a gas or vapor evaporating from the
cake during baking and a change in the concentration of the gas are
detected to judge the kind of the cake. According to a result of
the judgment, the heater is controlled. In this way, the present
invention realizes precise judgment of the cake, sufficiently
controls the baking of the cake at high precision depending on the
kind of the cake.
Various modifications will become possible for those skilled in the
art after receiving the teachings of the present disclosure without
departing from the scope thereof.
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